Investors left with whiplash over the stock market's volatile ride in the past few weeks should look for values on tech stocks during down days, said Matrix Asset Advisors' David Katz.

Buyers should remain wary of stocks like Facebook and instead focus on "dull" and "old" technology companies such as Microsoft and Cisco, Katz said Wednesday on CNBC's "Squawk on the Street." They each trade around 15 times earnings and are well-positioned for growth, said Katz, who focuses on finding value stocks. Investors also shouldn't try to time the market, Katz said.

"It's impossible on a day-to-day basis to figure out what's going on," Katz said. "We would definitely try to focus on a longer-term view, at least a six to 12 months. Set that time frame and don't chase up days like today. Do your buying on the days where it looks like everything is coming to an end and everything is selling off."

Katz blamed worsening geopolitical tensions for last week's tech-focused selloff. As for this week's up-and-down moves, the stock market has become harder to read, Katz said. He added that the psychology of the market seems better this week.

"You had momentum investors blowing out of the Nasdaq in the last few weeks," Katz said. "We think you can buy selectively in the Nasdaq. We would not chase the momentum stocks of the day."